Sadly, it is. A lot of incidents happen with nuclear plants because of shoddy maintenance and generally speaking, people not caring. I know of a reactor fairly close to me in New York had radioactive steam venting to atmosphere for almost a month before a stuck valve was found and repaired.
I consider nuclear power to be not only viable, but the only way. The only problem with them is how carelessly they are handled.
As for Chernobyl… they were simulating a blackout power-failure in a minimally staffed reactor, with most safety systems manually shut off? As a test? Following a test? On a reactor that was in an extremely unstable condition because of said earlier tests?
I know Russia’s standard protocol of “Boss said so, so do it, Period” during that era… but I’m very open to the idea that this was not an accident.